1. Field of the Invention
This invention relates to a vehicle-to-vehicle distance calculation apparatus and method.
2. Description of the Related Art
Calculation of vehicle-to-vehicle distance is important in order to prevent vehicular accidents. In order to achieve this, there is a system that detects the shadow of the vehicle traveling ahead of one's own vehicle and calculates vehicle-to-vehicle distance using the position of the shadow and a vanishing point (Patent Document 1). Further, there is a system that detects an obstacle by utilizing a vanishing point (Patent Document 2) and a system that detects whether an object is a moving body by utilizing a vanishing point (Patent Document 3).
[Patent Document 1]: Japanese Patent Application Laid-Open No. 2002-327635
[Patent Document 2]: Japanese Patent Application Laid-Open No. 2007-199932
[Patent Document 3]: Japanese Patent Application Laid-Open No. 2006-48338
However, since the position of the shadow of the vehicle traveling ahead must be detected in Patent Document 1, the system is comparatively complex and cost of development is high. In addition, there are instances where it takes too much time to calculate distance. Furthermore, since it is difficult to detect a shadow at night or on a snow-covered road, etc., there are instances where distance cannot be calculated. Further, in both Patent Documents 1 and 2, no consideration is given to calculation of vehicle-to-vehicle distance in a comparatively simple and accurate manner.